Appendicitis Acute appendicitis, atypical appendicitis, diagnosis, unusual presentation

can be presented by classic form in just over half of patients or atypical
symptoms in rest of patients. This issue can cause increase of morbidity
associated with acute appendicitis. The acute appendicitis diagnosis can be
particularly challenging due to the position of the appendix as related to the
cecum, the age of the patient, comorbidity or coexisting conditions. A high
clinical suspicion, mixed with the awareness of the significance of main
atypical features, will conduct clinician to reach the correct diagnosis.
Patients with a combined of atypical and typical signs and symptoms are
candidates for more evaluation and diagnostic testing. The purpose of this article
was to review the unusual presentation of appendicitis in the recent
literatures and describe the rare cases of
acute appendicitis with related history and imaging.

Key words: Acute
appendicitis, atypical appendicitis, diagnosis, unusual presentation


appendicitis is a common cause of acute abdomen in the emergency departments
1,4,18.Appendicitis can be presented by classic form in just over half of
patients or atypical symptoms in rest of patients1,4,25. Therefore, acute
appendicitis is a common missed diagnosis in the emergency departments. 1This
misdiagnosis can increase morbidity and even mortality in patients with appendicitis
1,4,15,18,25. A perforated appendix is a main complication with 16%
incidence rate. The perforation can form an appendicular mass or
retroperitoneal abscess 27.This issue highlights the
importance of considering an

appendicitis when evaluating a patient with acute abdomen in order to prevent
any delay in diagnosis of acute appendicitis and decrease the mortality and
morbidity 18.Portal and mesenteric thrombophlebitis is a rare complication of
acute appendicitis. This condition is due to ascending infection of acute appendicitis
and is a life threatening disorder 15. The purpose of this artilce was to
review the unusual presentation of appendicitis in the recent literatures and
describe the rare cases of acute
appendicitis with related history and imaging.


Why diagnosis
challenging for acute appendicitis:

The acute
appendicitis diagnosis may be particularly challenging due to the position of
the appendix as related to the cecum, the age of the patient, comorbidity
including cystic fibrosis or coexisting conditions such as pregnancy 1,2,3,11.

1. The
position of the appendix: The inflamed appendix is covered
by the overlying organs (far from the abdominal wall) when places in position
of retro-cecal and retro-ileal. Therefore, it’s symptoms are less severe and may
not face with shift of pain from the epigastrium to the right lower quadrant in
this situation 1. Consideration of different positions of the appendix in
relation to the anatomy of retroperitoneal compartments is crucial in
understanding the etiopathogenesis of some unusual presentation 11,12,13,27.Urinary
frequency maybe occur due to irritation of the ureter. Muscle guarding and
abdominal tenderness are minimal in this situation. Pain is usually limited to
the lower abdomen when the inflamed appendix places in pelvic position and rectal
examination causes tenderness 1.

2. Acute
appendicitis in children: The diagnosis of acute
appendicitis in childhood is difficult rather than adults due to atypical
gastrointestinal symptoms 6,20,25. Four of each 1000 children less than 14
years of age will be diagnosed with acute appendicitis. Forty-four percent of
children with appendicitis presented with six or more atypical presentations 25.
Misdiagnosis of appendicitis has been reported 7.5-12% of children less than 15
years and more than 57% in children less than 6 years 6.

3. The
acute appendicitis in elderly: Diagnosis of appendicitis in the
elderly is usually delayed due to mild symptoms even with advanced inflammation
1. 4.The acute appendicitis in pregnancy: Acute appendicitis in
pregnancy is also misdiagnosed due to highlight of obstetric disorders.
Abdominal tenderness may be move to the umbilicus or right subcostal area
because of cecum displacement 1,3.Figure 2 show an algorithm for the
evaluation of pregnant patients with suspected appendicitis 3.

Figure 2.
An algorithm for the evaluation of pregnant patients with suspected




Unusual etiologies of acute appendicitis:

1. Infectious: Streptococcus
can involve appendicitis but peritonitis with streptococcus pyogenes–based
septicemia are rare. They are often primary, with no portal of entry, and more
common in immunocompromised or diabetic patients 6. Their severity is high
with a 25-40% death rate particularly when related with a mixture of toxic
shock syndrome or with its regional tropism (necrotizing fasciitis) 30. The uncommon
causes of appendicitis are parasites such as Ascaris lumbricoides , Enterobius
vermicularis ,and Strongyloides stercoralis5. Some infectious like pathogenic
species of Yersinia can also causes of 25% of acute granulomatous

2. Acute
granulomatous appendicitis: Isolated inflammatory form of
granulomatous appendicitis is rare (2%) and different from Crohn’s disease.10,28
The bowel involvement has been seen in just 5-10% of patients10,28. Noninfectious
causes of granulomatous appendicitis are diverticulosis, sarcoidosis, tumor
causing appendiceal obstruction, foreign body reaction, and idiopathic
granulomatous appendicitis. Infectious causes granulomatous appendicitis are
Yersinia, Mycobacterium tuberculosis, Blastomycosis, Schistosoma, Actinomyces,
Campylobacter, Histoplasma capsulatum , and some fungi and parasites 10 ,28.

3. Acute appendicitis by
inflammatory bowel disease: The appendix sometimes involves by inflammatory bowel
disease including crohn’s disease and ulcerative colitis. In patients with ulcerative
colitis of distal colon ( sparing of the intervening colonic segment, named as
the appendiceal “skip lesion” or “cecal patch”) . Appendectomy (before the
onset of disease) maybe protect against developing inflammatory bowel disease
and decrease its severity 28.

involvement has been seen in 20-25% of Crohn’s patients under surgical
exploration and up to 50% in patients with ileal or colonic crohn’s
Thus, granulomatous appendicitis a rare presentation of Crohn’s disease.
Although, some patients with this condition are cured by appendectomy

4. Acute
appendicitis as a complication of acute pancreatitis: There is
a probability that an acute appendicitis be a rare complication of an acute pancreatitis.
Infection is transferred from the pancreas to the colon 19.

There is
controversy about the treatment of this type appendicitis. Some clinician agree
for supportive and conservative treatment (such as somatostatin analogue administration
without surgical intervention) for peritonitis of appendicitis

as a
complication of pancreatitis19 ,41.

5. Acute
appendicitis due to neoplasm: Primary neoplasms of the
appendix can present as an acute appendicitis. In one study, twenty-six (40%)
of the 65 patients with appendiceal neoplasms had presented with acute
appendicitis at first. CT scan of before operation was available in 22 patients
and just showed increased appendiceal diameter, wall thickening, and
periappendiceal fat stranding. Although, clinician believe that CT scan can
show the presence of underlying neoplasm in the majority of patients with
secondary appendicitis. 33

Unusual presentations of acute

1. Recurrent/ sub acute
appendicitis : Some patients can present with recurrent/ subacute episodes
of abdominal pain after a symptomless period of weeks or months after first
episode of appendicitis, as named recurrent appendicitis due to the transient
obstruction of the appendix lumen. Resolution of each episode is spontaneously
or after antibiotic therapy 7.Interval appendectomy is considered as the one
cause of granulomatous appendicitis due to a granulomatous reaction of a
protracted secondary inflammatory response to appendicitis and delay
appendectomy. 28.

2. Chronic appendicitis: Chronic appendicitis is
characterized by a continuous, and less intense abdominal pain for weeks or
months or even years ago due to the continuous partial obstruction of the
appendix lumen 7. A case report has described a patient with abdominal pain
and chronic appendicitis with unusual finding in the colonoscopy. Inflamed
appendicitis presented like a finger-shaped structure resembling a large
inverted diverticulum with adjacent signs of chronic inflammation in the
sigmoid 35.

3. Acute
appendicitis by mobile cecum and ascending colon: The prevalence
of mobile caecum and ascending colon is 10–20% in population but its very rare
causes of acute abdomen. The ascending colon and cecum can place in left upper
quadrant and the tip of inflamed appendix extended from cecum to umbilicus. If
cecum place more inferomedially from its normal anatomic position, the base of
the appendix locate retrovesically and its tip touch the iliac vessels 21.

left-sided appendicitis: Intestinal malrotation (1 out of
every 500 births ) and left-sided appendicitis (0.04%) are rare but physicians
should consider it if acute left-sided pain mimics appendicitis9,14,22,27.
Majority of case reports of left sided appendicitis were male with an age range
of 8 – 82 years. Most of them had situs inversus totalis then mid gut
malrotation 39.The predominant presentations of malrotation are the siting of
the ascending colon, cecum (and appendix) in the left side of the abdomen and
the right-sided placement of the duodenojejunal junction 14, 32. Patients
with malrotation not only have an increased risk of bowel obstruction, but also
have altered clinical symptoms for the common intestinal disorder such as
appendicitis 14. The clinical signs of cecal inflammatory disorders may be
misleading in patients with intestinal malrotation, thus delaying diagnosis and
increase risk of volvulus or intestinal obstruction 14. In a case report ,
patient presented with epigastric pain and vomiting and was diagnosed an acute
left-sided appendicitis by CT scan. In other case report , patient presented
with epigastric pain and had an intestinal malrotation with the cecum fixed at the
epigastric region . The inflamed appendix extending beside the left liver lobe

Thus, In
patient with undiagnosed congenital gut malrotation that an appendix locates in
the left lower quadrant of the abdomen can present with atypical symptoms of
acute appendicitis 22,32. Atypical presentations of acute appendicitis should be
considered in patients with abdominal pain and previous operation for
diaphragmatic hernia 29 ,40. A long appendix (length: 10 cm)
can be extend and its tip touches the medial wall of sigmoid colon and produces
a left lower quadrant pain in the patient 18,27.

5. Urinary
retention or bowel obstruction by acute appendicitis: A
perforated pelvic appendix or appendiceal abscess can cause of the urinary
retention or bowel obstruction due to walled of by the bladder, sigmoid and
rectum. Most of case reports were male 16,17.

6. Muscle
abscess or cellulitis by acute appendicitis : Muscle abscess or
cellulitis due to direct contamination of the retroperitoneum according to the
retrocecal position of the appendix, which results in the spread of pus into
the thigh or elsewhere through natural abdominal wall defects 11,24,26,27. Retroperitoneal abscesses
sometimes present with few symptoms and signs and its difficult for early
diagnosis. The high morbidity and mortality rates have been reported for this
complication 27. A CT scan is the key standard (100% sensitivity) for diagnosing
a retroperitoneal collection 27. An MRI is the main choice for showing any
intra muscular collection and roll out or in osteomyelitis. An MRI can
differentiate between an intra-articular pathology and a psoas abscess in a
patient with painful hip or tracked down through the inguinal canal 27. There
is a controversy for appendicectomy.The recurrence rate of appendicaecal mass
following conservative treatment varies between 3-25%. Some clinician recommend
a close follow up of symptoms mixture with investigations such colonoscopy for
roll out malignancy. The appendicectomy should be considered for symptoms recur
or persist27.

7. Fistula
due to acute appendicitis: The fistula from appendix is
often an internal fistula involving urinary bladder, ileum, cecum, duodenum, ascending
colon, meckel’s diverticulum and uterus 34,38.The occurrence of
appendico-cuteneous fistula is rare and have been reported few cases 34,37.
Appendiceal fistula is not the same as its following an appendectomy. The
mechanism is the spontaneous rupture of inflamed appendix into the adjacent
bowel or the skin. Then obstruction occurs due to appendiceal calculus,
malignancy or tuberculosis that prevents spontaneous closure 34 . The orifice
of this fistula can be placed in right buttock, right flank, groin , umbilicus
and iliac fossa 34,37. It means that external orifice cannot aid about finding
the origin of fistulous. The variable position of the tip of appendix
responsible for the variability in the position of appendico-cutaneous fistula

The most
common site of tip is retrocaecal position then retroperitoneal perforation of
appendix resulting in psoas abscess 34,38.This unusual psoas abscess around
perforated appendix prevent from spontaneous closure and caused persistence of
the fistula. Psoas spasm is a main physical sign and landmark for
retroperitoneal or intraperitoneal origin. You should consider that an
intraperitoneal pathology cannot be excluded in asymptomatic patient34. The
results of bacterial culture before surgery could indicate the nature of the
abscess being primary or secondary.The most common pathogen of primary psoas
abscess is Staphylococcus aureus, while in secondary psoas abscess faces with
mixed intestinal floras 38.The formation of complicated retroperitoneal
abscesses is a serious complication of perforated acute appendicitis. The
mortality rate is high in this secondary abscess (16.7%) and needs early
diagnosis 34. In atypical presentation of appendicitis, CT scan and MRI
images can provide better appendiceal visualization, extension of the pathology
and evaluation for surgical planning34,38 . The drainage of abscess can be
achieved by percutaneous and retroperitoneal approach or by laparotomy based on
CT findings38.An open appendectomy with excision of fistulous tract that is
the mainstay of treatment to cure the condition 34,37,38.

8. Mass
lesion due to acute appendicitis: A perforated appendix can
present with a mass in the right iliac fossa due to a large subcutaneous
abscess and enterocutaneous fistula 23,27.

9. Acute
appendicitis within a hernia sac: An inflamed appendix may be
rarely (0.13%) discovered within a hernia sac, most commonly in inguinal hernia
8. A perforated appendicitis within a hernia sac maybe present with
necrotizing fasciitis, too 12.

Pneumatosis intestinalis by acute appendicitis:  Pneumatosis Intestinalis with portal venous
gas is an extremely rare finding in acute appendicitis. It is usually
associated with intestinal infarction and has a poor prognosis. It is unclear
that how gas can enter to the portal venous system by acute appendicitis.
Patients are classified into two groups. The first and larger group are those
with transmural ischemia, systemic toxicity and a high mortality rate. The
second group are those without bowel ischemia or infection. The high
intraluminal pressure with mucosal disruption is seen in the last group. Portal
venous gas is seen with a wide range of pathologies which many of them do not
need surgery. It should be consider in the patient’s clinical condition as well
as other associated imaging findings 36.

Colonoscopy role in diagnosis of acute appandicitis with atypical

is an useful procedure in the diagnosis of acute appendicitis when there is
atypical symptoms for appendicitis or imaging studies are nondiagnostic 4.
Some case reports have described the diagnosis of acute appendicitis by
colonoscopy 4.

Figure .
Endoscopic view shows mucosal bulging and hyperemia at appendiceal orifice and
markedly edematous surrounding mucosa (A), close up view of inflamed
appendix orifice (B) , ulceration of surrounding edematous mucosa (C)




Figure . Endoscopic
view of appendiceal orifice shows swelling and hyperemia (A), the next
view after taking biopsy specimens and pus draining from the biopsy site (B)


Near half
of the patients presented with unusual signs and symptoms of acute appendicitis.
This issue can cause increase of morbidity associated with acute appendicitis. A
high clinical suspicion, mixed with the awareness of the significance of main
atypical features, will conduct clinician to reach the correct diagnosis.
Patients with a combined of atypical and typical signs and symptoms are
candidates for more evaluation and diagnostic testing.